TLC5951 Datasheet, PDF (29/46 Pages) Texas Instruments – 24-Channel, 12-Bit PWM LED Driver with 7-Bit Dot Correction and 3-Group, 8-Bit Global Brightness Control

TLC5951
www.ti.com
SBVS127B – MARCH 2009 – REVISED DECEMBER 2009
When the IC powers on, the grayscale data latch contains random data. Therefore, grayscale data must be
written to the 288-bit common shift register and latched into the GS data latch before turning on the
constant-current outputs. XBLNK should be low when powering on the TLC5951 to force all outputs off until the
internal registers can be programmed. All constant-current outputs are forced off when XBLNK is low. The data
bit assignment is shown in Table 8.
BITS
11-0
23-12
35-24
47-36
59-48
71-60
83-72
95-84
107-96
119-108
131-120
143-132
Table 8. Grayscale Data Bit Assignment
DATA
OUTR0
OUTG0
OUTB0
OUTR1
OUTG1
OUTB1
OUTR2
OUTG2
OUTB2
OUTR3
OUTG3
OUTB3
BITS
155-144
167-156
179-168
191-180
203-192
215-204
227-216
239-228
251-240
263-252
275-264
287-276
DATA
OUTR4
OUTG4
OUTB4
OUTR5
OUTG5
OUTB5
OUTR6
OUTG6
OUTB6
OUTR7
OUTG7
OUTB7
DC/BC/FC/UD Shift Register
The 216-bit DC/BC/FC/UD shift register is used to shift data from the DSSIN pin into the TLC5951. The data
shifted into this register are used for the dot correction (DC), global brightness control (BC), function control (FC),
and user-defined (UD) data latches. Each of these latches is described in the following sections. The register
LSB is connected to DCSIN and the MSB is connected to DCSOUT. On each DCSCK rising edge, the data on
DCSIN are shifted into the register LSB and all 216 bits are shifted towards the MSB. The register MSB is always
connected to DCOUT. When the IC is powered on, the 216-bit DC/BC/FC/UD shift register contains random
data.
DC/BC/FC/UD Data Latch
The 216-bit DC/BC/FC/UD data latch contains dot correction (DC) data, global brightness control (BC) data,
function control (FC) data, and user-defined (UD) data. Data can be written into this latch from the DC/BC/FC/UD
shift register. Furthermore, DC/BC/FC data can be written into this latch from the 288-bit common shift register.
At this time, UD data are written to bits 199-215 in the 216-bit DC/BC/FC/UD shift register data latch. When the
IC is powered on, the DC/BC/FC/UD data latch contains random data.
MSB
215-199 198-192 191-184 183-176 175-168 167-161 160-154 153-147 146-140
LSB
27-21 20-14 13-7 6-0
¼ ^User
Defined
Bits 16-0
FUNC
Bits 6-0
BRIGHT BRIGHT BRIGHT DOTCOR DOTCOR DOTCOR DOTCOR
Bits 7-0 Bits 7-0 Bits 7-0 Bits 6-0 Bits 6-0 Bits 6-0 Bits 6-0
OUTB0-7 OUTG0-7 OUTR0-7 OUTB7 OUTG7 OUTR7 OUTB6
DOTCOR DOTCOR DOTCOR DOTCOR
Bits 6-0 Bits 6-0 Bits 6-0 Bits 6-0
OUTR1 OUTB0 OUTG0 OUTR0
User Function Global Brightness Control
Defined Control
Dot Correction
Figure 46. DC/BC/FC/UD Data Latch Configuration
Dot Correction Data Latch
The dot correction (DC) data latch is 168 bits long. The DC data latch consists of bits 0-167 in the DC/BC/FC/UD
data latch. This latch contains the 7-bit DC value for each of the TLC5951 constant-current outputs. Each DC
value individually adjusts the output current for each constant-current driver. As explained in the Dot Correction
(DC) Function section, the DC values are used to adjust the output current from 0% to 66.7% of the maximum
value when the dot correction low adjustment range is selected and from 33.3% to 100% of the maximum value
when the dot correction high adjustment range is selected. The adjustment range is selected by the range control
bits in the function control latch.
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